Patent GB-191302409-A (GB)
Title: Improvements in and relating to Selecting Devices for Telephone and other Systems.
IPC: H04Q3/42
Filed: 1913-01-29
Granted: 1914-03-02
Abstract: 2409. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. Jan. 29. Automatic and semi - automatic exchange systems; exchange systems.-Relates to systems of the kind described in Specification 2302/13 in which the use of trunk-hunting numerical selectors is avoided by the provision of means for testing for an available outgoing trunk in the required direction, that is to the required group or section of the exchange, before the selector is taken into use. As soon as a selector capable of extending the call in the required direction has been found by the so-called pathfinder, the latter is released and made available for other calls. The present invention relates (1) to certain circuit connexions which are described but not claimed in the prior Specification, (2) to a two-wire system for a small exchange in which connexions are made by single co-ordinate selectors controlled by side-switches as shown in Figs. 35, 36, 37, and (3) to the application of similar principles to junction-line working between manual exchanges having no direct connexion. Two-wire system, Figs. 35, 36, 37. In this system each subscriber is provided with two switches D, V, of which the switch D is operated by the first set of selecting-impulses to find a non-numerical switch P from which trunks lead to link switches G capable of extending the call in the required direction. The switches P, V then hunt simultaneously for a link switch G. The selected link switch is then operated according to the first digit of the wanted line to select a final switch LW, Fig. 37, which is adjusted to the wanted line. The operations in detail are as follows- Operation of path-finder switches D, P to find a suitable link switch G. If subscriber J<1> wishes to call line 95, he transmits sets of 9, 9, 5 impulses. The first set of impulses are repeated by his line relay R through a slow-release relay V<2> to the motor magnet Da<1>, which rotates the wipers 16, 8, 33 to the contacts of a non- numerical switch P. As soon as the impulses cease, the relay V<2> opens the circuit of the magnet S, which moves the side-switch into its second position, wherein a circuit is completed from the battery B', Fig. 36, normal contact 22 of switch V, motor magnet Da2, relay V<3>, lead 18, off-normal contact 14 of switch P, relay V<5>, motor magnet Da3, contact 11, and wiper 13 to battery B<2>. The test leads 23, 24 of busy trunks incoming to or outgoing from the link switches G are connected by the relays V, V<8> to the poles of the divided battery B', B<2>, so that the switches P, V continue to rotate until they simultaneously find disengaged trunks. When the switch V stops, the relay V<3> opens at contact 29 the circuit of the magnet S, which moves the side-switch into its third position, wherein it remains until the path-finder switches are restored after the operation of the link switch G. Operation of link switch G, Fig. 36. A link switch, capable of extending the call in the required direction, having been selected, the calling subscriber again sends in nine impulses, which are repeated by relay R over contact 40, Fig. 35, to relay R', Fig. 36, and by the latter to slow-release relays V<7>, V<10>, and the motor magnet Da4. When the switch G comes to rest, the relay Pa1 energizes in series with a relay C, Fig. 37, and (1) disconnects the relay R<1> from the a-lead, and (2) opens the restoring- circuit of the motor magnet Da4. Release of path-finder switches D, P. During the transmission of the second set of impulses, the relay V<2>, Fig. 35, energizes the magnet S, and when these impulses cease the side-switch is moved into its fourth position, in which the motor magnet Da3 is earthed through the interrupter U and rotates the switch P until the off-normal contacts 14, 34, 48 are opened. The contact 34 open-circuits a relay HR, thus energizing the motor magnet Da1, which returns the switch D to normal. Operation of connector LW, Fig. 37. The final set of five impulses is repeated by the relay R, Fig. 35, over the lead a to the motor magnet Da5 and relay V<9>. As soon as these impulses cease, the slow-release relay V<9> opens the circuit of the magnet S1, thus moving the side-switch into its second position, in which the test relay Pa2 is connected to the test wiper. Busy test and signal. If the wanted subscriber is engaged, the relay Pa2 is not energized, and the side-switch remains in its second position, the busy generator Su being connected to the calling line over contact 78. When the calling subscriber hangs up, a single impulse is sent by the relay R, Fig. 35, to the relay V<9>. which closes at contact 79 the circuit of the release magnet M, and earths at contact 64 the test lead 65 so as to release the other selectors as described later. Supply of ringing current. If the wanted subscriber is idle, the relay Pa2 is energized, and by closing contact 56 moves the side-switch into its third position in which the ringing- relay L is intermittently energized and connects the ringing-generator to the called line over contacts 60, 61 and 54, 55 closed by the relay Pa2. During the first non-ringing interval after the subscriber replies, the relay Y is energized, and disconnects the ringing relay, at the same time energizing the slow-release relay V<9>, to prepare the release circuits at contacts 54<1>, 64. Release. When the called subscriber hangs up, the relay Y closes at contact 66 the circuit of the connector release magnet M, and also earths the lead 65 at contact 63. The relay Pa1, Fig. 36, is thus short-circuited and completes a circuit for the motor magnet Da4, which returns the link switch G to its normal position. When the calling subscriber hangs up, the relays R, V<1> de-energize, and the latter closes contacts 74, Fig. 35, and 72, Fig. 36, thus completing a circuit for the motor magnet Da2, which returns the selector V to normal. Manual systems, Fig. 38. The principle of simultaneously testing the incoming and outgoing lines can be applied to junction line working between manual exchanges having no direct connexion, a call from exchange A to exchange B being made through a link exchange C. If a calling line T, Fig. 38, in exchange A is to be connected to exchange B, the operator inserts the plug Pc in a jack Jc individual to the exchange C, this selective operation corresponding to the numerical operation of the selector D, Fig 35, in the system just described. The selector V then hunts for a disengaged junction to the exchange C, while the selector P hunts for an idle junction from the exchange C to the exchange B. When the selectors P, V simultaneously find disengaged lines, they come to rest, and call signals Sp, Ep are lighted at exchange C. The operator at exchange C completes the connexion by inserting the indicated plug Pb into the indicated jack Jb. The circuit arrangements of the selectors P, V closely resemble those of the selectors P, V, Fig. 36.